Setembro, 2000 An. Soc. Entomol. Brasil 29(3) 547 BIOLOGICAL CONTROL Predatory Activity of Phytoseiid Mites on the Developmental Stages of Coffee Ringspot Mite (Acari: Phytoseiidae: Tenuipalpidae) PAULO R. REIS, ADENIR V. TEODORO AND MARÇAL PEDRO NETO EPAMIG-CTSM, Caixa postal 176, 37200-000, Lavras, MG, Brasil. An. Soc. Entomol. Brasil 29(3): 547-553 (2000) Atividade Predatória de Ácaros Fitoseídeos Sobre os Estádios de Desenvolvimento do Ácaro da Mancha-Anular do Cafeeiro (Acari: Phytoseiidae: Tenuipalpidae) RESUMO - Através de bioensaios realizados em arenas com 3 cm de diâmetro, confeccionadas com folhas de cafeeiro flutuando em água, foram estudadas as fases do ácaro da mancha-anular do cafeeiro Brevipalpus phoenicis (Geijskes) quanto à preferência pelos diversos estádios do desenvolvimento dos ácaros predadores Euseius alatus DeLeon e Iphiseiodes zuluagai Denmark & Muma. Os experimentos foram conduzidos em laboratório a 25 ± 2ºC, 70 ± 10% de UR e 14 horas de fotofase. O estádio do ácaro vetor mais predado foi o de larva, seguido pelo de ninfa e ovo. A fase adulta teve muito pouca predação. De modo geral, a fase mais agressiva dos predadores foi a de fêmea adulta, seguida pela de ninfa. A fase de larva foi a menos eficiente na predação. As médias de predação de E. alatus e I. zuluagai para as diferentes fases do B. phoenicis foram respectivamente: larva (79% e 90%) > ovo (47% e 83%) > ninfa (40% e 77%) > adulto (1% e 18%), o que demonstra que I. zuluagai mostrou maior atividade predatória que E. alatus. PALAVRAS-CHAVE: Rhabdovirus, controle biológico, ácaro-plano, Brevipalpus phoenicis, Euseius alatus, Iphiseiodes zuluagai. ABSTRACT - By means of bioassays performed in arenas of 3 cm in diameter, manufactured with coffee leaves floating on water, the phases of the coffee ringspot mite Brevipalpus phoenicis (Geijskes) were studies on the preference by several developmental stages of the predaceous mites Euseius alatus DeLeon and Iphiseiodes zuluagai Denmark & Muma. The experiment was conducted in laboratory at 25 ± 2ºC, 70 ± 10% RH and 14 h photophase. The preferred stage of coffee ringspot vector virus was the larva followed by nymph and egg. Adults were least preyed on. In general, the most aggressive phase of the predators was the adult female followed by the nymph; the larval phase was the least aggres- sive. The average predation of E. alatus and I. zuluagai for the different phases of B. phoenicis were, respectively: larva (79% and 90%) > egg (47% and 83%) > nymph (40% and 77%) > adult (1% and 18%). This result indicated that I. zuluagai is more aggressive than E. alatus in relation to its predation upon B. phoenicis. KEY WORDS: Rhabdovirus, biological control, flat-mite, Brevipalpus phoenicis, Euseius alatus, Iphiseiodes zuluagai. 548 Reis et al. The mite Brevipalpus phoenicis Because the predatory mites I. zuluagai (Geijskes) has been reported on coffee trees and E. alatus are found on coffee (Pallini in Brazil since 1951 (Anonymous 1951). Filho et al.1992) and citrus trees (Reis et al. More recently, it was related to coffee ringspot 2000), on which B. phoenicis is also an im- (Chagas 1973) caused by a virus of the portant pest, this study was conducted to in- Rhabdovirus group (Chagas 1988). vestigate the predatory activity of those pre- Coffee ringspot was not considered of any daceous mites on each developmental stage economic problem until 1988 (Chagas 1988). of B. phoenicis. Since 1990, and specially in 1995, infestations by B. phoenicis and ringspot have been re- Material and Methods ported in the state of Minas Gerais causing intense leaf dropping on coffee trees, mainly The predation potential of the predaceous in the region of Alto Paranaíba. The presence mites was studied through bioassays using of the mite being also found in other coffee arenas of 3 cm in diameter, made of healthy growing regions of Brazil, both in arabic and unsprayed coffee leaves (C. arabica) (Coffea arabica L.) and canephora (Coffea floating in water. The study was conducted at canephora Pierre) coffee species. the acarology laboratory of the Centro Re- The mite B. phoenicis is often found as- gional de Pesquisa do Sul de Minas, of sociated with the predaceous mites Empresa de Pesquisa Agropecuária de Minas Iphiseiodes zuluagai Denmark & Muma and Gerais - EPAMIG, in Lavras (MG), at 25 ± Euseius alatus DeLeon (Acari: Phytoseiidae), 2ºC, 70 ± 10% RH and photophase of 14 h among others. Phytoseiids have been widely (daylight lamp). studied and considered the most effective Five arenas were placed to float on water predatory mites (McMurtry et al. 1970, in open dishes petri 15 cm in diameter by 2 Moraes 1991). Pallini Filho et al. (1992) re- cm in depth. Each arena contained a central ported a number of species of predator mites hole to fit the passage of a pin. The pins were on coffee trees, among them, I. zuluagai and fixed by the head to the bottom of the dish E. alatus, which were the object of this study. with silicone glue before adding the water, in The consumption of prey by phytoseiid mites such a way as to prevent touching each other has been investigated chiefly for mites of the or the walls of the dish. Water was added daily family Tetranychidae. Smith & Newsom to prevent the arenas from touching the bot- (1970) showed that adult females of the tom, serving as a permanent barrier to pre- phytoseiid Neoseiulus fallacis (Garmam) are vent the mites from escaping (Reis et al. the most efficient phase in relation to preda- 1998). tion on Tetranychus urticae Koch (Acari: Bioassays were performed using every Tetranychidae), while other stages of the possible combinations between each devel- predator still contributed to the control of the opmental phase of I. zuluagai and E. alatus pest. Using eggs of T. urticae as prey, Ma & (larva, nymph, male and female) and the prey Laing (1973) found that larvae of Neoseiulus B. phoenicis (egg, larva, nymph and adult fe- chilenensis (Dosse) did not feed, and that the male). A control was included, consisting of females were more efficient in predation than each prey phase without predator. Each com- males, mainly during the oviposition period. bination and respective control had ten repli- Gravena et al. (1994) estimated the preda- cations. Each arena received a predator and tory activity of the phytoseiid Euseius 20 prey at the desirable phases. After 24 hours citrifolius Denmark & Muma upon citrus of the introduction of the mites into the arena, leprosis mite, B. phoenicis, and found that the numbers of completely preyed, partially larvae, nymphs and adult females were simi- preyed, naturally dead, dead in water and liv- lar and or superior in the predatory activity ing mites were counted. The mites, both preda- than adult males. tors and B. phoenicis, were obtained from Setembro, 2000 Table 1. Number (mean ± SE) of individuals of B. phoenicis (n = 20) at different developmental stages preyed upon by different stages of the predaceous mites E. alatus (E.a.) and I. zuluagai (I.z.) within a period of 24 h. Stages of B. phoenicis /predator species Predator stages Egg Larva Nymph Adult E. a. I. z. E. a. I. z E. a. I. z. E. a. I. z. Check 0.0 ± 0.00 c 0.0 ± 0.00 c 0.0 ± 0.00 c 0.0 ± 0.00 c 0.0 ± 0.00 c 0.0 ± 0.00 d 0.0 ± 0.00 b 0.0 ± 0.00 c Larva 2.7 ± 0.44 b 1.9 ± 0.38 c 14.8 ± 0.59ab 5.7 ± 0.75 b 7.2 ± 0.67a 2.1 ± 0.41 c 0.0 ± 0.00 b 0.1 ± 0.18 c An. Soc.Entomol.Brasil Nymph 4.2 ± 0.61 b 18.4 ± 0.56a 16.0 ± 0.54ab 18.1 ± 0.75a 9.6 ± 0.44a 15.1 ± 0.67ab 0.2 ± 0.21ab 2.4 ± 0.48ab Adult (male) 5.5 ± 0.70 b 11.7 ± 0.82 b 13.4 ± 0.69 b 16.2 ± 0.79a 3.8 ± 0.46 b 11.0 ± 0.70 b 0.1 ± 0.18ab 1.4 ± 0.56 bc Adult (female) 18.2 ± 0.49a 19.8 ± 0.25a 17.7 ± 0.49a 19.7 ± 0.26a 10.3 ± 0.50a 19.8 ± 0.26a 0.5 ± 0.2 a 7.0 ± 0.70a CV (%) 32.3 21.3 11.6 24.5 21.6 10.0 23.9 50.9 29(3) Means followed by same letter in the columns do not differ among them by Tukey’s test (P £ 0.05). 549 550 Reis et al. maintenance rearing (Reis & Alves 1997b) order of preference, by the larvae of I. which enabled the utilization of mites of uni- zuluagai were: larva (29%) > nymph (11%) form age. > egg (10%) > adult (1%). By the nymphs were: egg (92%) > larva (91 %) > nymph Results and Discussion (76%) > adult (13%); by the females were: egg (99%) > nymph (99%) > larva (98.5%) > Results obtained are shown on Table 1. adult (35%). By the males of the predator Throughout the observation time, neither natu- were: larva (81%) > egg (59%) > nymph ral death nor death in water of the mite B. (55%) > adult (7%) (Fig. 2). phoenicis was observed in the check treat- The average predation of nymphs, males ment. Thus, no correction for predation was and females of E. alatus and I. zuluagai for performed. the different phases of B. phoenicis were, re- The phases of B. phoenicis consumed, in spectively: larva (79% and 90%) > egg (47% order of preference, by the larvae of the preda- and 83%) > nymph (40% and 77%) > adult tor E. alatus were: larva (75%) > nymph (1% and 18%), which showed greater preda- (39%) > egg (14%) > adult (0%).